This invention relates to DC-to-DC power conversion of the zero-current switching, forward, single-ended type.
One such converter (disclosed in Vinciarelli, U.S. Pat. No. 4,415,959, issued Nov. 15, 1983, incorporated herein by reference) converts energy from a voltage source for delivery to a current sink using a transformer that has a controlled amount of effective secondary leakage current. On the source side of the transformer, a switch is connected in series with the source and the primary winding of the transformer. The switch connects the source to and disconnects it from the primary winding in a succession of power transfer cycles. On the load side of the transformer, a diode and a capacitor are connected in series with the secondary winding. The capacitor and the effective leakage inductance define a time scale for the cycling of the switch such that the switch is cycled on and off at times when the current through the switch and the diode are essentially zero. Energy stored in the capacitor is transferred to a load via an inductor (current sink). Thus power is efficiently converted from a voltage source to a current sink.